Dennis McKenna — The Depths of Ayahuasca: 500+ Sessions, Fundamentals, Advanced Topics, Science, Churches, Learnings, Warnings, and Beyond (#523)

Artist's rendering of Dennis McKenna.
Illustration via 99designs

“To my mind, science, properly pursued, only deepens the mystery. It doesn’t take the mystery away. It shows you how mystery exists profoundly at every level.”

— Dennis McKenna

Dennis McKenna (@DennisMcKenna4) has spent more than 40 years researching the interdisciplinary study of Amazonian ethnopharmacology and plant hallucinogens. He has conducted extensive ethnobotanical fieldwork in the Peruvian, Colombian, and Brazilian Amazon.

His doctoral research at the University of British Columbia focused on the ethnopharmacology of ayahuasca and oo-koo-he, two tryptamine-based hallucinogens used by indigenous peoples in the Northwest Amazon.

He is a founding board member of the Heffter Research Institute and was a key organizer and participant in the Hoasca Project, the first biomedical investigation of ayahuasca used by the UDV, a Brazilian religious group. He is the younger brother of Terence McKenna.

From 2000 to 2017, he taught courses on ethnopharmacology as well as Plants in Human Affairs at the Center for Spirituality and Healing at the University of Minnesota. In 2019, in collaboration with colleagues, he incorporated a new nonprofit, the McKenna Academy of Natural Philosophy. He emigrated to Canada in the spring of 2019 with his wife Sheila and now resides in Abbotsford, British Columbia.

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#523: Dennis McKenna — The Depths of Ayahuasca: 500+ Sessions, Fundamentals, Advanced Topics, Science, Churches, Learnings, Warnings, and Beyond

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What was your favorite quote or lesson from this episode? Please let me know in the comments.


Want to hear another episode with someone who’s not afraid to tread Amazonian rainforests in the puddles left by Richard Evans Schultes’ footsteps? Lend your ears to my discussion with ethnobotanist Mark Plotkin about Schultes’ proclivities as a trickster in the shamanic tradition, how a shaman in the northeastern part of the Amazon cured Mark’s foot pain instantly when no one else could, the “holes” in Western medicine’s understanding, hallucinogenic frogs, the risks of ayahuasca and other Amazon-derived hallucinogens, and much more.

#469: Dr. Mark Plotkin on Ethnobotany, Real vs. Fake Shamans, Hallucinogens, and the Dalai Lamas of South America


  • Connect with Dennis McKenna:

Blog | Twitter | Facebook | Instagram

  • Connect with McKenna Academy:

Website | Donate | Twitter | Facebook | Instagram | YouTube


  • Dennis describes his first meeting with legendary ethnobotanist Richard Evans Schultes, the ensuing correspondence, and how it began a journey he wasn’t quite expecting. [06:53]
  • After spending 15 years in the sweltering Amazon, can Richard Evans Schultes be blamed for the disarming state in which Dennis first encountered him at Harvard? [20:15]
  • What made Sanford Siegel such a unique, creative scientist, and why is science such a crucial framework for serious explorers of the psychedelic ecosystem? [22:51]
  • What is Dennis’ “tortured” definition of ethnopharmacology? How many of the medicinal compounds we take for granted today have a cultural back story? [27:52]
  • On the government-subsidized 1967 Ethnopharmacologic Search for Psychoactive Drugs gathering, its 50th anniversary (and corresponding volumes edited by Dennis), the intervening Controlled Substances Act, and recent, surprising findings related to ayahuasca. [30:58]
  • What is the UDV? [37:19]
  • Does the UDV differentiate between different types of brews for different purposes? What is the organization’s view of ayahuasca as a medicine, and why have its adherents allowed outsiders to investigate its mysteries with scientific curiosity? [39:47]
  • There’s not just one type of ayahuasca. What has been Dennis’ experience with some of its other varieties, and what practical purposes might be served by learning more about them? Why has further study been elusive thus far? [44:01]
  • What is Brugmansia, and what makes it so scary? How is it used, and what should you do if you discover that some has ended up in your ayahuasca? [48:09]
  • Reasons to be cautious with sight-unseen mercenary “shamans” offering to guide you on psychedelic journeys in strange lands from which you might not return. [51:17]
  • The pros and cons of how ayahuasca tourism has altered its traditional use in recent years. [54:24]
  • If ayahuasca is something that can change your life after just one use, how does Dennis justify taking it over 500 times in his life, and what has it taught him? [58:14]
  • What circumstances might dictate Dennis’ decision to partake of ayahuasca, and why does he believe microdosing ayahuasca might actually be of benefit — even if he’s skeptical of the efficacy of microdosing other compounds? [1:02:54]
  • That time when things went terribly askew: the experiment at La Chorrera (as chronicled in Terence McKenna’s True Hallucinations), and why anyone undertaking such an exploration needs to be prepared for this possibility. [1:08:13]
  • Was it just an unusually bountiful and constantly consumed supply of psilocybin mushrooms over a long period of time to blame for sending the experiment at La Chorrera off the rails? [1:14:24]
  • When is it appropriate to let things play out — as they eventually did for Dennis at La Chorrera — or commit someone having this kind of experience to a professional psychiatric intervention? [1:17:16]
  • What is The McKenna Academy of Natural Philosophy, why was this nonprofit started, and what projects is it currently facilitating? [1:24:22]
  • Is The McKenna Academy a 501(c)(3) tax-exempt organization? [1:29:36]
  • Who else is involved in The McKenna Academy? [1:30:03]
  • What projects would be on Dennis’ shortlist with the proper resources, and what’s on the plate? [1:31:09]
  • New thoughts on the Stoned Ape Theory as Terence McKenna’s Food of the Gods is about to be reprinted. [1:32:38]
  • How much financial support will The McKenna Academy need to accomplish its current roster of goals, and what’s its highest priority? [1:36:15]
  • What is a voucher specimen? [1:38:50]
  • How many plant species are estimated to exist in the Amazon today, and how many have been thoroughly investigated? What are we doing to increase this percentage, what might we hope for from forthcoming discoveries, and what can we do to safeguard the bounty from these discoveries for the people who have been their stewards for millennia? [1:41:33]
  • How quickly can our tax-deductible donations fill The McKenna Academy of Natural Philosophy’s coffers to $600,000? Let’s find out together! I’ll start. [1:45:25]
  • Dennis’ billboard and parting thoughts. [1:49:54]


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10 Replies to “Dennis McKenna — The Depths of Ayahuasca: 500+ Sessions, Fundamentals, Advanced Topics, Science, Churches, Learnings, Warnings, and Beyond (#523)”

  1. Hi Tim (or anyone who reads this)

    Long time listener first time commenter. I was wondering what your thoughts are on vaporised DMT freebase compared to ayahuasca, do you think it could offer similar benefits?

    Some people think that the short duration of the trip prevents meaningful inner work. What about the effect on neurocognitive functions? Because there is both the experiential and neurocognitive aspects of the psychedelic experience.

    The discussion on harmalas was interesting. Some people combine harmaline, harmine and tetrahydroharmine with vaporised DMT for MAO inhibition to extend the breakthrough experience. It can also change the character of the trip

    Combining sublingual harmalas with vaporised DMT can consistently provide a breakthrough experience where you are back to baseline by the 30 minute mark. It seems this could be an effective approach.

    Do you think this could provide similar benefits or is the experience too fleeting? Could it be associated with higher risks than ayahuasca?

    All the best

  2. Hi Tim. Wasn’t able to listen to this podcast, unfortunately, though I would have liked to. Although you’ve been a big influence on me, I had to stop listening to your podcast some time ago, the reason being, your intro: ‘Ladies and germs’ makes me feel like killing myself. I live in a country (the UK), where men account for 75% of suicides and the biggest killer of young and middle-aged men is suicide. My life has been destroyed by misandry and there’s nowhere I can go these days without running into some type of degradation of men or masculinity – including, unfortunately, your podcast.

    If we’re to turn the tide on the male suicide epidemic, we really need men who’ve got ahead in life to start looking out for those who are falling irretrievably behind. I know you’ve given a lot of time and resources to the therapeutic use of psychedelics, etc. However, perhaps a simpler (and greater) contribution to reducing despair and suicide among men would be to stop referring to us as ‘germs’. Then I’d be able to listen to your podcast again, which has been a great source of inspiration for me down the years through many difficult times. Cheers.

  3. Learn a lot from, and enjoy your show a great deal. Request that you stop addressing your audience as “Ladies and germs”. Feels disrespectful and not sure why you came up with that. Especially enjoy Peterson interviews. Thanks for listening, Rich Carling. [Moderator: contact info removed from post but preserved in intake field.]

  4. Hi Mr. Tim!

    I know that this isn’t a comment related to your blog post or podcast (I promise to listen to it after this! :D) But I’m writing in the hopes that you’d be able to read a letter I wrote asking if you could send a birthday message for my partner, who is one of your biggest fans. Here is the letter! I hope you consider this! (The Google Doc is restricted – I wouldn’t want others except yourself to read it– but I do hope you get to read this! )

    I’m commenting here because it is your most recent blog post, and you probably would respond either through Twitter or here.

    For the other readers reading this, I hope you’re not put off by this comment! I know it’s quite a long shot and I super respect Tim’s time, but I wanted to try.

    All the best,


  5. Dennis and Tim;
    I too have almost 600 sessions of entheogens over the last 40 years and a huge amount of information on entheogens, Ultimate Reality, human existence, spiritual illumination, et al. Any possibility of getting together to compare notes? [Moderator: links removed.]

  6. I am interested in knowing what is that substance that you spoek about that is similar to a drug that makes people forget what happens?

  7. You STILL say “ladies and germs.” Please, why? Not funny, never was. Many people have brought this up. Please listen to your listeners.

  8. First-time listener and really enjoyed it, don’t know what all the fuss about “ladies and germs” is, and couldn’t think it less relevant. The content is good. Thanks!